Method of oxidizing steel or iron sheets.



- J. E. CRNAHN L A. J. MASKREY.

METHOD 0F OXDZNG STEEL OR IRON SHEETS.

APPMGANON FILED JUNE 11, 1913.

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Emilra sfrnrss .are raros JOHN' E. CARNAHAN AND .ARTHUR J, MASKREY, 0F CANTON, OHEIO.

METHOD 0F OXIDIZING STEL OR IRON SHEETS.

Specification of Letters Patent.

Patented ct?, tte.

Application filed June 11, 1913. Serial No. 773,001.

To all 'whom 'it may concern Be it known that We, JOHN E. CARNAHAN and ARTHUR J. MASKREY, both citizens of the United States, and both residing at Canton, in the county of Stark and State of Ohio, have invented a new and useful Method of Oxidizing Steel or Iron Sheets, of which the following is a specification.

The invention relates to the oxidation of the, surface of annealed steel or iron sheets for the purpose of giving 4them a uniform bluish color. Ordinary processes of anneal ing such sheets frequently produce a va rying color of oxidation thereon merging from a darker blue color adjacent to the edges into a distinctly lighter blue or silvery color on the middle portions of the sheet, which different colors are sometimes emphasized by the subsequent processes in finishing the sheets..

`The object of the present invention is to carry `out the annealing process in such a manner as will result in a uniform oxidationgiving a uniform blue color to the surfaces of the sheets throughout substantially the Whole extent thereof; which is attained by inclosing the sheets during the annealing process in a sand sealed protecting box located within the usual sand sealed annealing box, as illustrated in the accompanying drawings forming part hereof'in which, j

Figure 1, is a cross section of the annea1- ing box showing a protecting box inclosing a pack of sheets therein. Fig. 2, a longitudinal section on line 2 2, Fig. l. Fig. .3, a

' plan section on line 3--3, Fig. 1.

Similar -numerals refer to similar parts throughout the drawings.

The annealing box is composed of the annealingpan 1, having the rim ianges 2 thereon, and the annealing pot inverted on the pan; the joint between the rim of the pot and the flange of the pan being sealed or luted with sand Ll in the usual manner. The protecting box may be composed of the bottom plate 5, preferably provided with the foot ribs (S for supporting it slightly above the bottom of the annealing pan, and the protecting pot 7 inverted upon the plate and provided with the iiange 8 surrounding the rim and spaced at an interval therefrom by the connecting bars 9, between which flange and rim is placed the sealing or luting sand 10. The cavity of the pro tecting box is preferably shaped so that while its walls are vnot in actual contact with the sides and top of the pack, they are in close proximity thereto; thus reducing to a minimum. the amount of air or lo)ther gas within the cavity of the protecting For carrying eut the annealing and blu ing process, thepack of sheets l1 is placed upon the bottom plate 5, and after inverting the protecting pot 7 thereover, the joint between the pot and plate is sealed er luted by sand filled in between the rim of the pot and the adjacent flange. The protectng box is then incloseo within an ordinary annealing box and the rim joint there" of is sealed or luted with sand in the usual manner, after which the annealing boeiend its contents are placed in a furnace and heated to an annealing temperature of about f means for separating the sheets and the particular.v oxidizing agent employed, not being an essential feature of the present invention.

lt has been found that' by annealing the i sheets in a sand sealed protecting box within the ordinary sand sealed annealing box, the subsequent separation and oxidation thereof results in a substantially uniform color throughout the entire surface of each sheet, and prevents the formation of irregu-vk la;l discolorations in different parts of the sheet and the formation of an excessively deep oxidation ox scale at or near the edges of the sheet. This result may be and no doubt is attained because the protecting box Within which the sheets are inclosed during the annealing process shields the sheets from the products of combustion, some of which find their way within the ordinary annealing box. Moreover, -the dead air space which is formed between the walls of the two boxes and between the Wall of the protecting pot and the pack of sheets, prevents .up a suction of t an excessive heating of the corners and edge portions of the sheets, with the result that the heat is substantially equalized Within the protecting box and Athe sheets are brought to a substantially uniform temperature thron hout their Whole extent. Fur:- thermore, t e anealing box and its contents should be continuously hested Without checking or reducin the temperature therein during the amica in process, tovavoid setting Le products of combustion into the snnealing 4and protectingboxes by the cooling .and consequent contraction of the air non gas therein.

We claim:

1. The method of oxidizing annealed steel o1 iron sheets consisting in inclosing the sheets in a scaled protecting box within a sealed annealing box during the annealing process and then separateiy exposing the heated sheets to an oxidizing agente 2. The method of oxidizing annealed steel or iron sheets consisting in inclosing the sheets in a sand sealed protecting box Within a sand sealed annealing box during the annealin process and `then separately exposing t e heated sheets to an oxidizing a ent.

3, The' method of oxidizing annealed steel or iron sheets consisting in inclosing the sheetswithin a sealed annealing box during the annealing process and then separately exposing the heated sheets to an oxidizing agent.

#L The method of oxidizing annealed steel or iron sheets consisting in inciosing a pack of sheets in a sealed protecting box Within a sealed annealing box, the Walls of the protecting box being in close proximity to the sides and top of the pack during the annealing process and then sepa'ately exposing the heated sheets to an oxidizing agent.

Vitnesses:

MARY A. GAVANAUGH, Emmen SCHMIDT. 

